I was given a lg bag of whole corn 9 weeks ago by mistake. My chickens ate it up...with no ill side effects. BUT, I made darn sure they had a full grit container at all times to eat. I am not an expert, but my 51 Buff Orpingtons are still alive and well. They love anything corn LOL.
So the answer is, its ok, kust make sure to give them grit along with it.
I dont know about young chicks, mine are 7 months old now. I am going to test the whole grain. It seems to me that if they can eat whole corn, then whole grain would be ok.
But I do intend on buying it cracked, just so it is easier for them.